This application is the national phase of international application PCT/GB98/02007 filed Jul. 8, 1998 which designated the U.S.
This invention relates to a mechanism adapted to produce a plurality of different motions upon the application of a force thereto, with particular reference to fitness machines incorporating the mechanism.
There are numerous xe2x80x9cfitness machinesxe2x80x9d commonly used in gymnasiums. Such machines comprise multi-purpose weightlifting equipment - often termed xe2x80x9cmulti-gymsxe2x80x9d and various devices for improving aerobic fitness, such as exercise cycles, stepping machines and ski simulators, in which the action of cross country skiing is mimicked by, essentially, antiparallel linear translation of the user""s feet. Recently, so-called xe2x80x9ccross trainersxe2x80x9d have appeared, in which motion induced by the user is substantially elliptical. If the user is upright when using a cross training device, the motion is in the form of a horizontal ellipse, i.e. the major axis of the ellipse is in the horizontal plane.
These aerobic fitness machines are usually manufactured as separate devices, each device being dedicated to a particular task. In part this is due to the nature of different tasks performed, which is in large measure due to the different motions performed during use: with an exercise cycle a circular motion is maintained, with a stepping machine the motion is (vertical) linear; with a ski simulator the motion is (horizontal) linear and with a cross trainer the motion is, as described above, elliptical.
It would be desirable to produce a multi purpose aerobic fitness machine for a number of reasons. Firstly, substantial cost savings would result if a single device were manufactured, rather than a plurality of dedicated devices, each performing a specific function. Secondly, the amount of space required would be drastically reduced. These advantages would make a multi-purpose aerobic fitness machine particularly attractive for use in the home. However, the provision of a practical driving mechanism, which could enable the above described plurality of motions to be produced in a single machine, is a particular problem.
The present invention overcomes the above mentioned problem by providing a simple and cost effective drive mechanism, together with fitness machines incorporating this drive mechanism and having the above mentioned advantages.
According to the invention there is provided a mechanism adapted to produce a plurality of different motions of a member affording a point of application for a force comprising:
fixed disc means held in a fixed orientation; and at least one moveable disc means adapted to rotate around its origin and around the origin of the fixed disc means under the influence of the applied force;
in which:
the ratio of the radius of the fixed disc means to the radius of the moveable disc means is 2:1;
the position of the point to which the force is applied is radially variable relative to the origin of the moveable disc means; and
the moveable disc means is in communication with the fixed disc means so that rotation of the moveable disc means around the origin of the fixed disc means at a frequency f causes rotation of the moveable disc means at a frequency of 2f.
Preferably, the disc means comprise sprockets.
The position of the point which the force is applied to may be varied to produce linear. circular or elliptical motion. In this way, a plurality of different motions may be produced very easily, the type of motion being very easily changed by relatively small radial changes in the position of the point of application.
In one embodiment, the fixed sprocket has internal teeth, and the moveable sprocket is retained within the fixed sprocket in direct geared engagement therewith.
In another embodiment, the moveable sprocket is in communication with the fixed sprocket via a chain and a connecting crank. Tile mechanism may further comprise a rotatable crank in rigid connection with the moveable sprocket, the force being applied through the rotatable crank.
There is also provided a fitness machine incorporating a drive mechanism as described above. Such machines may be used as multi-purpose, aerobic fitness machines.
The member may comprise pedal means.
The fitness machine may be adapted to function as an exercise cycle, a stepping machine, a ski simulator and a cross training machine.
Furthermore, the machine may be adapted to produce motion on an ellipse having its major axis parallel to the body of the user.
The machine may be designed so that the user is recumbent.
The fitness machine may further comprise resistance means for inhibiting the rotation of the moveable disc means around the origin of the fixed disc means.